We are developing and using methods for studying a model system for sickled erythrocytes by investigating: a) Conformational changes in hemoglobins caused by reagents which might be effective in preventing or ameliorating sickle cell crises. Such reagents include covalently and non-covalently bound ligands, cations, ureas, glycols b) The initial rate of pregelation aggregation of deoxygenated pure HbS, HbC, HbF, HbA and their mixtures, as well as hemolysates and dialysates of homo- and heterozygote red cells. c) The perturbation of these rates of aggregation by the reagents in (a). d) The structure of deoxygenated reconstituted erythrocytes prepared by resealing red cell ghosts in the presence of pure hemoglobins, mixtures of hemoglobins, hemolysates and dialysates. Studies will be performed with phase and electron microscopy. e) The effect of reagents in (a) upon the reconstituted erythrocyte's structure, its membrane and its intracellular components when these reagents are: (1) present in the resealing solution and therefore inside the reconstituted cells, or (2) added after the cells have been resealed and washed, and therefore present only outside the cell unless they interact with membrane components and/or penetrate the membrane into the intracellular solution. Deoxygenated as well as oxygenated cells will be studied. The objective of this research is study the conformation of HbS, alone or in combination with other known components of erythrocytes, to evaluate the kinetics of formation of initial small aggregates, and to determine the behavior of concentrated (30g/100ml) solutions of HbS, mixtures of pure hemoglobins, hemolysates or dialysates from homo- or heterozygote red cells containing an S component, within a reconstituted erythrocyte. The effect of various possibly effective reagents on each of these steps will also be investigated. It is hoped that such data will expedite the development of better therapeutic modalities for sickle crisis patients.